In commercial aircraft, sensors may be located in fuel tanks to measure temperature, moisture content, fuel level, oxygen level, and other physical quantities. The sensors receive electrical power from a source outside the fuel tank, since Federal regulations prohibit power storage devices such as batteries and supercapacitors from being located within the fuel tank.
Electrical power may be supplied to the sensors by wires, which extend into the fuel tanks. The wires may also be used for data communications. However, the wires add weight to the aircraft. The added weigh increases aircraft operating costs. The wires also increase maintenance costs due to inspection.
In the alternative, the sensors may harvest energy from ambient sources (e.g., vibration, thermal and solar). However, harvesting from ambient sources may be unreliable and inconsistent, and, for confined structures such as fuel tanks, may not be viable.